Beagle Desktop Search

Beagle is a search tool that ransacks your personal information space to find whatever you're looking for.
Beagle is a Linux desktop-independent service which transparently and
unobtrusively indexes your data in real-time. For example:
* Files are immediately indexed when they are created, are re-indexed
when they are modified, and are dropped from the index upon deletion.
* E-mails are indexed upon arrival.
* IM conversations are indexed as you chat, a line at a time.
* Web pages are indexed as you view them (with a browser extension).
Beagle supports many different data sources and file formats.